Different OLAP's

Online Analytical Processing (OLAP):

Online Analytical Processing (OLAP) is the approach involved in providing analysis to multidimensional data. There are various forms of OLAP namely
    

Multidimensional OLAP (MOLAP) – This uses a cube structure to store the business attributes and measures. Conceptually it can be considered as multi-dimensional graph having various axes. Each axis represents a category of business called a dimension (eg location, product, time, employee etc.). The data points are the business transactional values called measures. The coordinate of each data point related it to the business dimension. The cubes are generally stored in proprietary format.  

Relational OLAP (ROLAP) – This uses database to store the business categories as dimension tales (containing textual business attributes and codes) and the fact tables to store the business transactional values (numeric measures). The fact tables are connected to the dimension tables through the Foreign-Key relationships. 

Hybrid OLAP (HOLAP) – This uses a cube structure to store some business attributes and database tables to hold the other attributes.